Can you copy and redistribute it without restriction? Sure.
Can you modify it and install the modified version on your computer without restriction? Sure.
The only thing you cannot do is redistribute the modified version. If you do that, there are some restrictions in place: you have to provide also the source of that modified version.
Also, about conditions on redistribution, the vast majority of all open-source software places at least some mild conditions, like the preservation of copyright and attribution to the authors, so if there is some kind of "gotcha" here, I don't think it has anything to do with copyleft.