You should ALWAYS do your best to use the package manager to install any missing package since it should know where to put in this case 638 Files (600 of those are the fonts) and 25 Folders specifically for your specific modifications to the distro.
If you must manually download look for the TDS zip in this case it is http://mirrors.ctan.org/install/fonts/baskervillef.tds.zip this file is TDS COMPLIANT that means you only need to unpack it in exactly the right location and it will be similar to the one downloaded by the package manager
I understand in your case you are off-line and cannot download as and when required, however I would strongly suggest you look at the possibility of downloading a full set of files to a single location (4 to 8 GB usb) such that your Tex Live package manager can use the local set when you need them. This is often done in a similar fashion to a network install where single users can call on a local repository. That would be simpler that frequently downloading single packages. One alternative is to obtain the Tex Live Annual (April) DVD and just update those parts of your system when needed.
I do not know if you may find W32TeX more suitable for your needs and both it's abTexinst package manager or the Standard Tex Live Setup manager can allow you to select and/or update large groups of packages without having to download the full collection. Just be careful not to mix them or else you could get version conflicts since W32TeX is now in 2019 release whilst TeX Live is still at 2018. IF you keep the packages on a usb stick with the manager you can then take it on-line to check for partial updates.
Back to your current issue
Beware the next step can replace an up-to-date set of files with an older version which is why you should use the package manager that will do most version checking.
For TeX Live you need to check where your texmf-local folder is by running
kpsewhich --var-value TEXMFLOCAL
If that returns nothing then you need to build AND SET one
When you unpack that TDS.zip you will see just 3 of the 25 folders (Doc Fonts and Tex) You very simply need to copy or move those 3 folders to your texmf-local folder and accept ALL overwrites necessary to replace any of the 638 files you may already have, this is necessary to keep all the new files at the same version.
You have now compromised your fonts and filename database (more than 1200 times) so need to tell the package manager what you have done and ask it to Update filename database (600+ ways) and Update fonts mapping tables (600 ways)
For Tex Live to update filename database you need to yet again run
for MiKTeX users its
Then for font mappings read and apply the following instructions
- Font map files: telling TeX Live about the new font here https://www.tug.org/fonts/fontinstall.html
NOTE where it says newfont.map in this case that is
updmap-sys --force --enable Map=BaskervilleF.map