Early bus services in Latvia

Hello

I have to travel from Ape to Riga and I have to arrive there by 12:00. Right now, the only option, which I suppose rational, would be to get a coach bus. However, when I look up the ticket sellers online, they say tickets for the earlier departures are unavailable or not sold on the internet. This limitation is applied despite the day. Can someone please explain the system? Do I have to physically buy the ticket from the busdriver or are they sold at the bus stop or what?

Here's the link to the online service:
https://www.bezrindas.lv/en/bus-tickets/choose/217/45/1/20260126/0/0/ad70949555b22d1fd62c6b7a8cd292a7eeec1013

Thank you