Listify password too strong

Hello. My website is https://www.letmebe.eu
The only way to subscribe on this website is through an invitation e-mail I sent to users.
When they click on the link in the e-mail, they get to a page where that have to choose a password. A lot of people tell me that the thé website requires a very strength password.

Can someone tell me how to reduce the strength of this password field?

Thank you in advance.