Have a look here:
The polling company they use is called Change Research. Have a read at their wikipedia:
This company is operated by Pat Reilly, a former democratic party campaigner and all the polls are done “online”. I wouldn’t be surprised if all the data was completely fabricated. I saw this article being discussed on reddit and there wasn’t a single (Biden supporter) questioning the integrity of the poll methodology or the polling company. They were all just patting themselves on the back and circle jerking each other over the “upcoming Biden landslide”.
This company also is only 3 years old so their polls probably have zero credibility.