how did they get the technology?

Andy Tracker (Matt's younger brother) and Miles Mayhem co created the M.A.S.K technology. Mayhem then murdered Andy and stole half of the Masks and vehicles created.

Matt vowing to bring Mayhem to justice for his younger brothers murder formed the M.A.S.K team with the remaining masks and vehicles.

This was all revealed in the comics but in one of the later episodes of the series Matt briefly mentioned that Mayhem helped to create the M.A.S.K technology.Although there was no mention of Mayhem killing Matt's brother most likely because it was a kids cartoon.

As for how Andy and Miles Mayhem came up with all this futureistic technology it could be argued that they were geniuses way ahead of their time like Steve Jobs.

Its treason then! (Palpatine - Star Wars ROTS)

In the episode "Green Nightmare", it was revealed that M.A.S.K. used a crystal as a power amplifier to charge their masks. The original crystal they used was given to Matt Trakker's father Andrew by a tribe of New Guinea Mudmen.

2016 launched a comic book series called "Revolution". The story it's telling is that Miles Manhiem/Mayhem used the help of G.I Joe to capture a Transformer and reverse engineer its technology to create the MASK vehicles and spectrum in what he claimed was to aid in Earths defence from the Transformers.