This beeper music is originally made by Zilogator in 2012 but this is a new 2019 version with a screen added by AAABand Group. You can download the file from AAABand Group's page here: https://zxaaa.net/view_demo.php?id=12427
If you are interested in demos you should follow AAABand on YouTube, because they upload all from this genre that is relevant for the ZX Spectrum and Pentagon.
Also be sure to visit their site if you are looking for some specific demos because they will most likely be there. The files is scl or trd but if you do not have Beta Disk 128 these files can also run on a DivIDE or DivMMC device (The program SAMdisk can convert scl files to trd files).