To import your photos into Meshroom, just drag them into the Images pane. Once the images are imported, you can click the Start button to begin processing.
Even with a small number of images, processing can take several hours to process.
Once the images are processed. you can load the model by clicking StructureFromMotion and then Load Model.
If you notice an area that didn't come out well, you can import more pictures to add detail.
The obj file for the model is stored in MeshroomCache/Texturing/[folder name]/texturedMesh.obj. The MeshroomCache folder is usually located where you saved your project file.