As you know the HPA is a bit flimsy as is silent on such issues. I don't know if there is national legislation in Spain, but somehow I doubt it. Perhaps Maria may be able to confirm etc?
I had need of arranging an AGM for a similar body in the UK - there is good online government Covid guidance. But after more consideration decided against the option of holding a "Zoom" style meeting - there were too many owners and a lot wouldn't attend being too challenged by the IT technicalities involved.
We ended up holding a kind of "meeting" by email in stages. Firstly explaining the position and asking the owners to vote by passing a Special Resolution to allow voting on the various options/subjects by email. This was unanimously supported, so the voting could subsequently take place later (following the prescribed notice period of delay).
This all sounds a bit cumbersome, but in fact it was a lot simpler and more meaningful than the usual AGM! I sent copies of the paperwork to the company who act as our Company Secretary who accepted the procedure as being in the spirit of our Articles of Association.
Not sure if this would be OK in Spain, but your Administrator or others may have an opinion. I reckon if it's explained properly, reasonable, transparent and democratic it should be accepted. But I guess this depends on the owners - some in Spain on our urb seem to love making a fuss about nothing!