@MarcusWöll
Hi there,
If your e-mail adress is still in use and is set to your OSM account, then you do not need to do anything. Once the option to login with username and password gets removed, then you can login by using the button to get a code through an e-mail. That message is there to remind everyone about this upcoming change. So you can just ignore it.
The ads on the webversion are a known issue, but needs to be solved by the company of the ad player. They do work, but sometimes the video won't be played and after a few seconds the pop-up closes. The Bosscoin should be added to your account. I just tried it and I received a Bosscoin even though the video didn't play and the pop-up closed after a few seconds.