vTPM support - do we have guide to add the vTPM support?

Now that you mention it, I had gotten a newer macOS VM working without trying the older version again, so let me just double check before I go and put my foot in my mouth saying it doesn't work for me. Mojave was giving me issues in 7.4.
I want to use Win11 and vTPM but might not have an issue if 7.4 works outright.
 
Does subscribing give you access for repositories that allow TPM in 6.4?
No, Proxmox VE has all features fully available for everybody, no open core only or the like. Subscriptions allow for more stable, more broadly and thorough tested package updates and for enterprise support (depending on the subscription level bought).

TPM is only available with Proxmox VE 7.1 and newer.