No idea...
Go to the laptop on which you installed the current Lazarus release. Load lazmapviewerpkg.lpk and press Compile in the package editor dialog - does the compilation of the package complete successfully? If yes, proceed and click "Use" > "Install". DECLINE the question to rebuild Lazarus. Close the package editor. Go to "Tools" > "Configure "Build Lazarus"". In the "Clean up" box check "Clean all" and "Switch after building to automatically". Click "Build" - it should work and complete the recompilation of the IDE including MapViewer, I did it many, many times. If it does not you must rename the file "Lazarus.old.exe" to "Lazarus.exe" (in your Lazarus installation) in order to restore the Lazarus version before attempting to install MapViewer.
A good candidate to explain abnormal behavior is the AntiVirus system installed. Always put the Lazarus and your project folders on the white-list of the virus scanner. Antivirus companies often detect FPC and its tools as malware because they are not widely used. You may also try to turn off AV during recompilation of the IDE, the process I described above. Get rid of any commercial scanner, and stick to the built-in scanner coming with Win 10; it has the least interference with Laz/FPC and is sufficiently good for protection (some tests even say it's better than the commericals, but I don't trust tests...).