Others have flagged, might be worth raising a ticket with IA support. I also get the popup, but when I click sign in it directs me to the Exchange project page and allows me to download.
I am using Chrome Version 89.0.4389.128 (although it has just updated 
)
Edit: just updated to Version 90.0.4430.72 and I don't get the popup. Although it is more likely that the website has cached/cookied my user information correctly, rather than the update making a difference.