your plugin insert a wrong url for verification in the verification mail.
I think your plugin will insert http:// before the main url from general wordpress config. So my normal domain (rechable) is https://www.nrw-carcoding.de - your verification links is http://https:/www.nrw-carcoding.de
there are missing one / and the url crashed.
Please do not disable other plugins without asking, its a live site!