RTE Player when in Ireland

I had similar issue. It turned out to be because I had registered the Roku when in the UK. Once registered it’s not clever enough to think about where it is in the world it just always applies the rules of where it was registered. 
I worked around it by factory reset of Roku and registering to a different email account. That then gives you the option of making the stick know it is in Ireland and then you can add the RTE app.