You can try to delete Your Buildt-in folder, restart TC, save a dummie, shut it down and then try one more time to install.
It may well be that there is something wrong inside it, that still hang in the system so to speak,
The "book" tell you should only delete everything inside the folder, well, im sort of lazy and allways delete the full Buildt-in folder, so far, no problems with that, but save you settings etc if you have done some changes, as TC will start up again in Default after this, and then re buildt your Buildt in folder again.
Maybe restart Your computer also, full of, wait 10-15 sec and then start it again, before you try to install the plugin.
It also can be that it is connected to Your build, in the same way as the LW plugin is, correct buildt number of plugin to match the buildt Version of TC, then you need to ask support for an updated link to download you plugin again
easy way to find the buildt in
type %appdata% in the run area when click on start inside Windows, lower left corner, that will bring you to Your Roaming folder, se the different steps inside the Attached png to where to go for the rest.
V20, V21, 2015/ 16/ 17/ 18/ 19 Pro. Platinum
Deluxe 2015/ 16/ 19
Windows 10 Home Premium 64 bit, 32 GB
NVIDIA Geforce GTX 780m, 1 GB