Depends on their contract and how many paid/unpaid leave they still have. I know someone who has already spent all of their leave this year and won’t be able to just take a day off (unless it’s special leave like a doctor’s visit or certain funerals, of course).
OP should probably talk to their employer about this or read the company handbook. I suspect they can request special leave to use this service, but if it’s not considered a “normal” doctor’s visit, there may be special rules (i.e. not planning appointments during important meetings).
Refusing OP would be pretty stupid, because OP can also go through the regular medical system and that won’t be online, and requires a GP referral, so any psychiatric help they may require through that system will cost at least twice the amount of time compared to giving an hour or so off to use the company system. In most companies I know of, there are rules about special leave that would entitle OP to leave beyond their normal time off to visit their doctor(s).