Quick wrap up - when I arrived at Aeroporto Mavalane, I saw several people queuing at a counter where you paid for the visa. I handed over my printed copy of the pdf and the guy asked for my credit card. I had reserved using the AMEX so that's the card I handed over, only to be told "no". OK ... no AMEX I guess so I gave my Visa card instead. (I was to find throughout Mozambique that AMEX is not accepted anywhere.)

Anyhow, the fee was exactly as advertised. Once charged, I was given an impressive-looking official receipt and another printout of my pdf; seems my printout wasn't sufficient - they need to print it out even though it's the same thing.

With receipt and printout in hand, I was able to then queue for immigration where passports were being stamped with great enthusiasm by both male and female officers. I wonder if they get repetitive stress injuries from the amount of force they put into their stamping. In any case, it was amusing to see and hear such vigour going into passport stamping.

Formalities over (less than 10 min) I was able to claim my luggage and then head out into Maputo.

Thanks again to ozymandias24 for posting the initial set of instructions - super helpful!