Can I use Open Goaaal! for team training sessions?

Yes; but it should be left in the same location, and in a secure training ground, as it's not designed for taking down and packing away after each session.  

And it should be positioned off the playing area to help avoid the guy ropes becoming a trip hazard *. 

The reason that Open Goaaal! works so effectively is because the net is tensioned between the 2 poles. Measurements have to be precise, and anchors and pegs are hammered firmly into the ground.  They are not designed to be easily removed.  

However the net can be raised off the ground between sessions to cut the grass or avoid animals damaging it.

* Please note that one of the guy ropes at each end encroaches in front of the goal-line and onto the playing area. This creates a risk of tripping, and so we recommend that it is positioned off pitch and used for shooting and goalkeeping practice rather than game-play.