question: How can STARTRAC give the expected T cell number based on TCR-seq?

[2015pp]

Dear sir,
I have some questions about STARTRAC-dist.
How can STARTRAC give the expected T cell number randomly based on TCR-seq?
How can STARTRAC caculate the expected cell number of **macrophage, dendritic, Neutriphil, Mast and epithelial cells in the result 1 of the article "COVID-19 immune features revealed by a large-scalesingle-cell transcriptome atlas", as researchers only had TCR/BCR-seq data?