If that statement is accurate, than that is the
problem. You need to install the correct .NET 5.0.x Desktop
Runtime. <- note there is no "Framework" in that title.
You don't say exactly what doesn't work, except that JTAlert
doesn't work with any WSJT-X version.
If you haven't been able to get JTAlert to work after 6 months of
trying (that seems like an exaggeration to me), I suggest your
next course of action is to find an Elmer who can assist in
resolving your broken installation.