OK. The System 7.5.3 downloadable from Apple was not a normal floppy-based system with a bootable first installation disk. The US version, as an example, had totally nineteen floppy-sized files. These nineteen files were distributed with a MacBinary encoding (.bin).
One would transfer (copy) the nineteen .bin files to the hard disk of the receiving computer (here, the PB 190) on 1.44 MB floppy disks. Once there, using StuffIt Expander 4.0.1 or 5.5, one would decode the nineteen .bin files. This would result in one .smi and eighteen .part files (together constituting one large disk image), supposed to be placed in a common folder on the hard disk. Double-clicking on the first file (the .smi) will mount the entire self-mounting image. The System 7.5.3 installer will be found in the mounted image.
Please post back if you do not have StuffIt Expander for this Macintosh computer.
You could make a bootable floppy on the PB 190 from a Disk Tools PPC file (http://download.info.apple.com/Apple_Support_Area/Apple_Software_Updates/English -North_American/Macintosh/System/Mac_OS_8.1_Update/Disk_Tools_PPC.img.bin) via the Make a Floppy command under the Utilities menu in Disk Copy 6.3 3 (https://support.apple.com/kb/DL1262?locale=en_US). StuffIt Expander 4.0.1 or 5.5 is needed to decode the .bin files here too. Please note that the Disk Copy utility is not used with the System 7.5.3 files.