How to annotate optimally a fungal genome without RNA-seq evidence?
The Maker documentation does include some instructions for training ab initio gene predictors, but it assumes an abundant EST database is available. (Assumptions about what kinds of sequences will be available for a draft genome assembly have changed drastically in the last decade.)
It may be worth exploring an iterative approach in any case. You can do a first-pass annotation with Maker using the evidence you discussed, along with ab initio predictions from Augustus (and I'd recommend SNAP as well). Each gene model will be scored by Maker with the annotation edit distance (AED), representing how well the gene model agrees with the evidence (0.0 is best). From this first pass, if you can identify a few hundred reliable gene models with good AED scores (or maybe even as many as one or two thousand), that should be plenty of training data. You could use these gene models to train a new model for Augustus, using Maker's instructions or Augustus' own instruction. (In my experience, it was quite a bit of work in either case.)