How to get the sample matrix programmatically, TCGA

Question

[pcomps49]

Hi, I would like to download the "sample_matrix.txt" (the file "Sample matrix: List of all samples where 1=altered and 0=unaltered") for different cohorts from TCGA programmatically. I know I can do this from the website if I select the genes beforehand for example by going to this link. However I do not know exactly which genes I want beforehand. I just want, for a given cancer type, mutation labels for all genes that have at least 25 mutations. This is quite difficult to do manually for some cancer types with hundreds of genes. I have tried to download the entire zip file ("blca_tcga_pan_can_atlas_2018.tar.gz") however I do not see the sample_matrix.txt file inside it.