torbrowser-launcher (tb-l) is maintained by Micah Lee (not Tor). tb-l downloads
Tor Browser from https://torproject.org for you, checks its signature, and
"installs" it to a hidden home directory for your user. The
officially-supported way to install Tor Browser is to download it yourself from
https://torproject.org, optionally checking the signature by following the
instructions here https://support.torproject.org/tbb/how-to-verify-signature/.
No matter how you obtain it, Tor Browser auto-updates itself.

A common problem with tb-l is SIGNATURE VERIFICATION FAILED. While you expect
this error when the Tor Browser download is corrupted/malicious, it's much more
likely in this case that tb-l's copy of the signing key is simply out of date
again and there's nothing seriously wrong. This is a reoccurring problem with
MANY issues on the tb-l issue tracker. See here for one such issue and the
latest fix.  https://github.com/micahflee/torbrowser-launcher/issues/481
