If you have NAT due to VM network settings, change it to bridged mode and it will be more straight forward. Naively digiESP does not support passive mode FTP.
Long time ago digi engineering has been trying to implement the passive mode to compile a new plug-in.
It was done for DEL 5.8.1. and might work for 5.7. you can try.
If the active mode fails, it will try in passive mode.
To install it:
1. Close the Digi ESP if it is running.
2. Uncompress the com.digi.workbench_2.0.0.zip file to obtain a new one called com.digi.workbench_2.0.0.jar
3. Go to the plugins directory of your Digi ESP, <installation_path>/digiesp/plugins (usually /usr/local/DEL-5.8/digiesp/plugins)
4. Rename the file com.digi.workbench_2.0.0.jar to com.digi.workbench_2.0.0.jar-original not to lose it.
5. Copy the uncompressed file to the plugins directory.
6. Execute the Digi ESP with –clean option:
• Open a terminal window and execute the command
#> /usr/local/DigiEL-5.8/digiesp/digiesp –clean &