Textmarker not downloading

I downloaded Textmarker using Firefox 96.0.1 (64 bit). I have
Thunderbird 91.5.0 (32 bit) and Windows 7. All I got was an enormous
strand of gibberish. Why can’t this succeed when other downloads do.
However, this is the first time I’ve tried to download a Thunderbird
add-on. Thank you

_locales/de/PK ù¢YSelŽõéa U
locales/de/messages.json­YMoe9½/°ÿ£“HF${æ``°pÆ1bL’YÀ™ñÅ@@©«Õ\u³’mg4˜Ûþ½ä7ä”›þØ>’ÝRKé&%$ÄR7}¼zUEÿõÏ06 †¤¥|Ç\±¿ì§ø¼
®–¤£úÛ„ô\‰•Á{ö û.+Sf2bÛÏaöá¿ñÊ>ÐÍÞ»x¯ifXB’YPA
‚øp’]yìêrüJHmp(r„/–›ÏRÖ9Lð÷–#ƒ©qé“ŒWºNóÈ}Ÿ¡ÈÇ«kÞIÙãu™ã‰óh²‘ržð%<éöäÆYa£Øã èÚ¾²ÉËJ±JÎ3š/)ac–

And continuing on …

Don’t download it. Install it in Thunderbird itself from the Tools, Addons part of the program.

Note there is a support email address on the addon page.

Dave – thanks so much for the instructions to install Textmarker from
Tools > Add-ons! Tom