Governmental borrowing vs. private/corporate.
While the majority of companies which will want to get space and restablish manufactureing and anything else (think Dempse's restaurants) on the major stations and other orbital platforms are going to have to raise funds through borrowing through banks, it is somewhat differnt at the government level. We won't get into government guarantees for corporate debtt.
Many of you will have at least heard of US Treasury Bonds, Notes and Bills. That's Bonds for long maturity (beyond 10 years), Notes start max 10 years and bills are less than a year. All of that typicaly has quaterly interest--in general. The Government is selling government debt to be paid off over time. Rates and repayment terms vary. Most governents do this to fund domestic programs, infrastructure improvements/project and other things like wars. They give "notes" payable at certain times and genearly based on the ability of the government abiilty to raise money through taxes and other sources. In the case of the SEM it's primarily on the positive cash flow & profit of the Junction and then whatever the normal tax revenues are for everything else.
Which is why High Ridge wouldn't sign a Treaty with Haven because he would have been REQUIRED under the terms of the tax laws -actualy it would have been more or less automatic- to reduce the special tax rates enacted for the War with Haven.
Sometimes the notes/bonds etc are secured by something- in this case would have 1st call on funds generated by the Junction and terminus fees. Bonds tend to be be things going to 30 years but essentialy you are giving "written" promises to pay people who are often INVESTING in the government(s). This works at National, State, City/Town levels as well as for various other governmental opeations like utility and road commissions.
In the specific case of Manticore, we understand that SEM is shipping a lot of materials (refined "scrap from earlier captured/partialy destroyed Havenite warships in the Manticore system plus parts of the destroyed Home Fleet and now all that mostly usless junk that was SLN SDs) to Beowuld in partial payment and or agreed on exchange for manufacturing all sorts of things-including parts for warships and weapons for rebuilding the Manticore orbital infrastructuer. If nothing else, providing- where they can- already refined metals and materials rendered from starship scrap will offset at least part of the cost instead of having to buy it from someone else.
But in the long term, the government is going to have to foot the bill for much of the base construction of the major stations and of course rebuilding the military manufacturing and support structure.
Private companies will need to fund their part. And much of the private manufacture will have to pay their own way. God only know how complex the leasing arrangements on a multi 10 kilometer long space station with some part of the Government as the primary owner of the "space"
You really don't want the author to go into the detail or it would be a book or two just for that- without doing much to advance the plot

And SEM is importing/hireing workers from at least Beowulf for contruction in their system and to help train SEM citizens in the skills etc. They need to rebuild the workforce as well as the facilities and manufacturing. They will bring people in from Talbott and Silesia if they can get them. Skills and experience.