A long time ago, you could download files straight from the Bananas website, but that was disabled a few years ago (I wish they would bring it back, honestly).
It is possible to transfer the file from your OpenTTD installation on Android to your PC. The file will be located in /storage/emulated/0/Android/data/org.openttd.dsl/files/content_download/ .. but it's a PITA to get to.
Since you said you were playing on JGRPP, I'll instead point you to the enhanced version of ISR 1.0.2 which includes support for JGRPP's "bridge over station" feature.
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