Hit on "Sources."
Then hit on "Add Source."
Then hit on "Add New Source."
Then follow what it says and add a source from ancestry.com. Be sure to copy the source address in ancestry.com and paste it in where it says, "Web Page URL," below.
That is absolutely insane to go through all that to add a source.
When someone clicks on it, you can't see the source unless you are also an Ancestry member.
I get po'd when someone posts an Ancestry source and doesn't give you a clue as to what the record is about.
I don't have that much time.
It is possible to generate a "share" URL for an Ancestry source that anyone can view. (I'm not a subscriber, so I don't know the steps.) These are always preferable to use in citations, regardless of where you're adding them.
Also regardless of where your adding it, a citation should always include a summary of what is in the source. This is one reason I consider FS's (and Ancestry's) auto-citations to be worthless. They're so full of pointless boilerplate that they fail to convey what the record is, how to find it again, and what it says.
I will put Ancestry sources in the FS list of sources, yes. In a couple of cases I have noted the page numbers, and manually looked through the same record batch in FS to find the source, and then will add the FS source to the record and delete the Ancestry source. Funny that they have always been indexed, but don't seem to come up on the search results. Usually, however, I don't have time for all that and will just put the Ancestry source there and move on. I have been puzzled by why searches don't always work in FS, but I assume people are on it and working to fix it.
The share option does not give you viewable information, by the way, or it did not when I tried it on myself. It seems to tell you only that information has been found and the name of the record, for example, 1920 Census. https://click.email.ancestry.com/u/?qs=802c3a3114763759a49cf75a8da45cf30d0e7e5c08ef94ca133f0cc9e7dbc2a3ca51b61adafacd554f9645c6aa2d04b000bd4574137fdd3ea2765306da898367
Try that link and let me know if you get more.
That's a really weird share link: it has a placeholder image instead of the actual census page.
Here's what they're supposed to be like: https://www.ancestry.com/sharing/21675347?h=9854d0
I wonder if something changed this summer, when the method of accessing the function was changed? WikiTree G2G discussion about it: https://www.wikitree.com/g2g/1287333/ancestry-sharing-url-location-moved?show=1287333#q1287333
I suspect Ancestry may be controlling which images can be shared. When I go to the image of the 1920 census record for my great granfather, there is no sharing function. The sharing function is only available on the indexed screen for it. Your example is a different kind of record. I got the same for passenger lists, city directories and a passport application. I think Ancestry must have changed something.
I have no objection to sources from other websites being added, but users adding them should appreciate it is often the case they cannot be viewed by those who do not have a subscription to that site. Even when a subscription is not required, the link provided often just leads to the Home page of the website.
Incidentally, I have added many FamilySearch sources that can only be viewed from a Family History Centre (or Affiliate library) or, in some cases, have been withdrawn so cannot be viewed at all.
I would advise not to delete any of these (inaccessible to you) sources as:
(1) They might be of use to other users (without less restrictions on access of the material).
(2) Even if a URL has been withdrawn, it just might be reinstated in future.
(I'm glad I did not delete 1851 E&W census sources, when they were "replaced" some years ago. Instead I marked them all "Old version" - but the "new version" URLs of these records soon became useless, as the "old version" ones were reinstated, making them the "current" ones!)