Someone said :
GLEN was one of the first national organisations to work on HIV as far as I know - it got funding as far back as 1996 -
HIV Ireland is a new organisation which was only Dublin based until recently
Just to clarify, HIV Ireland is the new name of the Dublin AIDS Alliance, which was established in 1987. So it's not a new organisation by any means, just a new name for one of the oldest working on HIV in Ireland. You're quite right that historically they have been Dublin focused, but they are trying to be more active in other parts of the country as well, so chose a name to reflect that.
As for why GLEN got the funding, my guess would be that it was largely because Tiernan Brady (who is director of GLEN's Gay HIV Strategies sub-group) has been pushing to make rapid testing available in Dublin for years. He'd testified about it in hearings in the Oireachtas several times and likely had been talking directly to the former health minister about it during the development of the National Sexual Health Strategy. In addition, he'd already established connections with Deirdre Seery from the Cork Sexual Health Centre and GOSHH in Limerick, both of whom were already doing rapid testing and are also getting money from the grant to expand their work.
HIV Ireland has put a lot of time and effort into setting up their (excellent!) STI screening service and (this is my speculation anyway!) probably were not interested in taking on the new rapid testing project anyway.