Sorry but after full re-install from scratch (On Win10 I've remove all version Lazarus + TMS everywhere, even in Appdata directory))
There's always some probleme, I've follow strictly instruction from video and create a new project but :
1/ No unit1.html file created
2/ I've put instructions for Bootstrap 5.0.1 in project1.html and no css effect is shown (btn btn-primary for button)
I think there's something wrong in your last version or it miss something to do particular to install/use with lazarus with Win10.
3/ your demo project in tms default install for lazarus show an error because it miss some property to one component with last lazarus tms version.
Give me the solution please.
Thanks