Welcome @ChristinaP
This has come up before and the answer given was
So your applicant hasn’t blocked you they are no longer THS members .
If you have another way of contacting her ( phone number ) you can ask her if she is going to renew her membership before the date of your sit .
Or make private arrangements with them but you won’t get any THS support or be covered by THS insurance if the sit is arranged with someone who is not a paid up member.
You should also check with member services that this is not a sitter who has been suspended (Updated) Confirmed House Sitter Profile No Longer Active - Phone # Not Working - What Should I do?