cannot login to a subsite – only to the root

I had a lot of trouble with a sudirectory install until I saw this:

Giving WordPress Its Own Directory

and followed the instructions exactly.

Basically you have one .htaccess in the root. This redirects to the subdirectory. The subdirectory contains a root-like install with its own .htaccess. Your site address settings are both https://www.sitename.com and not https://www.sitename.com/subsite

I don’t know if your setup is like mine but hope this helps.

I’m trying to reproduce but I’m unable to so far… What type of site collection (Modern or Classic and template used) and subsite (template used) are you TellSubway using and how is your user accessing the permissions of the subsite.