"Unfortunately it won't let me enter without an ID"
Can you share with us the message that you are receiving when you attempt to save your AncestryDNA test info?
When you click inside the box "Click here to select DNA test" and select AncestryDNA (not Maternal or Paternal Lineage options), no other information is required to enter your AncestryDNA test. There are boxes for entering optional information in which you can add your Ancestry username and/or ID info associated with other sites, but none of that is required. If you don't have any optional info to include, or if you do but don't want to include it, just click the "Add Test" button after you've selected AncestryDNA test, leaving the other boxes empty.
My AncestryDNA test has been entered on my profile without any of the optional info. I didn't include my Ancestry username since my name on my profile here is what displays on my DNA test results at Ancestry. And I've not currently uploaded my AncestryDNA test results to any other sites, so I don't have an associated ID to enter in either of the additional optional boxes.