This is a 7-Zip compressed file. It uses high-ratio compression (usually LZMA or LZMA2) and is an open-source alternative to .zip or .rar .
If you are unsure what is inside "Alotta Comp," you can investigate without fully extracting by using these steps: Alotta Comp 7z 003
Right-click the file and run a scan with your antivirus (e.g., Windows Defender) before opening. This is a 7-Zip compressed file
"Comp" often stands for "Compilation." Check if the file sizes of the internal items match standard media formats (MP3, WAV, MKV). Alotta Comp 7z 003