The system requirements for Sumatra PDF are "Windows Vista, 7, 8, 10, 11", which suggests the 64bit version of Sumatra PDF. However, only the 32bit version is included in the PAF.
Due to memory restrictions, the 32bit version of Sumatra PDF cannot open big files (either one huge file or several big files). This is a problem when Sumatra PDF is used as a comic book reader. High quality cbr/cbz are often several hundred MB in size, and some are >1GB.