Utd are in the championship one division below the premiership but they've taken quite a few Prem players in so it's expected that they'll walk this league and be a decent premiership side.
I don't think it was particularly popular that they were allowed to enter at level 2 most felt they should start at the bottom and work their way up but the league were desperate to get Utd back involved as the womens game still has a big problem attracting an audience both at games but also on TV.