ACER Nitro 5 AN515-54-52NB - Upgrade SSD or HDD

Dominic100

I'm looking to upgrade my Acer's hard drive and was wondering what the max capacity and whether I can have an extra HDD or SDD or both. I'm ideally looking to get a HDD in the 2.5" bay; would like to have 2 tb but think the my max would only be 1tb. Also could I have a SDD there instead just in case I change my mind and what would the max capacity be?  

I was eyeing up this one below: 

https://www.ebay.co.uk/itm/WD-1TB-2-5-SATA-Internal-Hard-Drive-Disk-Laptop-HDD-WIN-MAC-PS3-PS4-24-7-HDD/183351566350?hash=item2ab09ae00e:g:5A4AAOSwSlpbXvtG

My specs are: 

Geforce GTX 1050 
Core (TM) i5-8300H CPU 
RAM: 8GB 
250 GB SSD c-drive (pre-installed) 

I also have these dual m.2 Support + one HDD slot. I'm not too familiar with m.2 Support. What is this please? 

Thanks