A PC version and Quest version of your avatar are exported to your account every time you “Upload to VRChat” in the Avatar Creator. Depending on what system you or others are using, the appropriate version of your avatar will be displayed - you shouldn’t have to do anything but design, export and spin up VRChat. After some handshakes between some servers happen, your freshly minted avatar can be found in the "Avatar" menu inside VRChat in the "Other" row.
In addition, there are only 3 slots within the VRChat "Other" section for avatars. Therefore, users can only load 3 avatars at a time from the Tafi Avatar Creator.