It appears that you have a newer version of F-droid in another profile than the one you're trying to install.
Android doesn't allow that for security reasons. F-droid notoriously serves an old version of the app on the homepage, which causes this issue.
You have two options here:
1) Download F-droid's latest version from here, and install that:
2) Install Droid-ify/Neo Store (they're the same app, it was recently rebranded to Neo Store) from here:
Neo Store is more modern and an overall better experience, and will also support unattended updates soon, unlike F-droid.
As always with F-droid, keep in mind that it has several issues, and make your choices accordingly.
Hope this helps!