We used it last December. You have to do your calculations carefully to check if it is worthwhile. You have to use the system for more than a week or so. For us it was as we saved pretty much twice what we paid. You can either buy it from a D Bahn travel centre when you get there or buy it in advance like we did. I bought ours via the Munich transport site. The English language version was easy to use. You buy your subscription for, in your case, August and then cancel it the next day to avoid being charged every month. It doesn't matter which site you use to buy the ticket.
It is very easy to use in that you simply hop onto whichever bus, tram, U Bahn or Regional Train you wish to use. There are no gates at train stations. You will be occasionally checked by a ticket inspector so you must always have your phone with you and your passport. As far as I am aware it is only electronic. We were checked about twice in 25 days both times on regional trains. But we didn't visit Berlin on that trip and I know there are a lot of inspectors there.
Remember that it doesn't cover trips on the high speed trains like IC, ICE, EC or Flixtrain. It does not allow travel in 1st class. If you are on the 'wrong' train and your ticket is checked you will be fined - we saw/heard it happening.
This guide explains how the 49-Euro-Ticket, D-Ticket or Deutschland Ticket works as a tourist or as a resident.
allaboutberlin.com
transporthttps://www.mvv-muenchen.de/en/tickets-and-fares/frequent-travellers/deutschland-ticket-d-ticket/index.html site - MVV.