You cannot walk INTO the parking structure to access the trams, at least not easily. It requires a lot of backtracking by using the pedestrian bridge that goes over
Disneyland Drive. And then standing in the lines for security and then the trams.
If you are staying at this hotel, you just walk into Downtown Disney and then to the parks. Walk up Disneyland Drive, cross at Magic Qay and then join the walking path into Downtown Disney that ends near the former ESPN zone. The security check there is super quick to go through. You can then take the monorail into Disneyland or walk to the Esplanade to DCA.
It's a 20 minute walk all the way to the Esplanade.